A significant part of the data transferred via mobile networks is video traffic in the streaming mode. The most modern streaming technology is dynamic adaptive streaming over HTTP. This technology is used, for example, by HTTP Live Streaming (Apple), Smooth Streaming (Microsoft), HTTP Dynamic Streaming (Adobe) and DASH standard. In this technology, the server stores several copies of a video file, each one coded with different parameters, for example, different resolutions and bit rates. The higher the bit rate is, the faster radio channel you need to transfer the video and the higher the quality of individual frames will be. The copies are split into independent segments synchronized by time. This allows you to rewind forward without loading all the segments, and also to switch between different bit rates when necessary.
From the client's point of view, video quality is perceived as good not only when its bit rate is high but also when there are no delays (also known as stallings) in playing. These delays appear when the client's input buffer becomes empty, i.e. the client is watching the video segments quicker than they are coming via the radio channel. When using a mobile network, one of the reasons for that is that the base station to which the client is connected has a limited time-and-frequency resource. This resource, in its turn, can be exhausted when it is congested by a large number of clients connected to the same base station. Because of the congestion, the transfer rate in the radio channel becomes lower for the most clients than the bit rates available on the server, leading to delays in playing.
From the prior art, we know ways to control video data flow via a network. For example, European patent 1872536 which is the closest analogue of the applied invention describes a way to control the transfer of data packages from the server to a client when the server switches between different versions of streaming, depending on the state of the client's buffer. The same multimedia contents, for example, a particular video sequence is preliminarily coded with various bit rates and stored on the server. However, this method requires storing a huge number of versions for each data flow. Moreover, even having a lot of versions does not guarantee that for every particular case the best possible version will always be available.
Hence it appears that there is a need for a new technical solution about the control over network streaming of video data to a user device which would provide high speed, simplicity, efficiency, minimum loss in quality and maximum satisfaction of the users.